I need to provide stable power source for 6 3V dc motors. I’m using small coin vibration motors for nokia 2630, don’t now exact specs. Two of them will work up to 100% and the rest will go as far as 60%. What kind of battery do I need ? Would 7V do the job? I’m using Fez Panda II.
What is the stall current of the motor? You then need to scale that out to your 6 motors, and then your regulator (taking your Vin down to 3v) needs to be able to supply that current. Then once you’ve figured that out, you need to make sure your input source can also provide that current
That’s the problem, I don’t have any information about motor, except for voltage…
May that help 
Take a breadboard, take a lab power supply set to 3V and measure the current using a ampmeter…
I haven’t got motors yet, I want to prepare everything because I’m a bit late with project…